Circuit breaker



Patented Oct. 7, 1941 CIRCUIT BREAKER Robert L. Frank, Detroit, Mich,assignor to Bulldog Electric Products Company, Detroit, Mich., acorporation of West Virginia Application February 3, 1940, Serial No.317,095

12 Claims.

This application relates to switches or circuit breakers which aremanually operable for normal circuit conditions and which openautomatically on the arising of a circuit abnormality, such as overload.

A common type of circuit breaker or switch includes engaging contacts, ahandle for moving one of them to and from the other, which isstationary, and a spring which tends to move the handle actuated contactout of closed circuit position. This action of the spring is inhibitedby a circuit responsive latch which normally holds the contact, butwhich releases it for spring movement on the arising of an overload.

Another known type, as disclosed in the patent to Evans, No. 1,360,280,includes two movable engaging contacts, one of which is manually movableand the other of which is constructed normally to remain stationary forbeing engaged by the manually movable contact, but is arranged to moveautomatically out of its engageable position on the arising of anoverload to open the circuit, the manually movable contact thenremaining stationary.

This application discloses a breaker of the last mentioned type havingnovel and desirable features.

One feature is the mounting of the circuit responsive contact directlyon a bimetal element, which is connected in circuit so as to be circuitresponsive, the contact thus moving in response to circuit conditions.

The bimetal part which mounts the circuit responsive contact hereof isso constructed that its movement, and that of its contact, to and fromits rest positions is a snap movement. Further, the bimetal part notonly moves its contact out of engaging position automatically, but inaddition, returns its contact to engaging position automatically.

Another feature is the provision of a snap action spring arrangement forthe handle actuated contact.

The invention will readily be understood upon reference to theembodiment of the invention disclosed in the single figure of theappended drawing which shows a switch casing l pivotally mounting, at H,a handle l2 riding in a slot M of the casing and connected by anover-center spring I 5 to an arm IS on which is insulatedly mounted themanually movable contact l1 con nected by pig tail l8 to terminalbinding post I9.

Adapted to be engaged by contact I1 is a circuit responsive contact 2|mounted on a bimetal snap disc 22 loosely secured at its center 25 tothe casing and loosely connected to a binding post 23.

The casing is formed with a stop 24 for determining clockwise movementof arm I6. 1

In closed circuit position, spring l5 biases parts |2|6 in suchdirections as to establish contact at |'|2|, with handle I2 abutting theend of slot l4.

Movement of handle I2 to theright, reverses parts |2-|6 with a snapaction to move contact H from contact 2|. Return movement of handle l2returns contact I! to contact 2| with snap action.

On overload, disc 22 will snap and its free part will reverse itsposition, to separate contact 2| from contact 11. Such action will takeplace even if the handle |2 be held, mischievously or otherwise.Thereafter, disc 22 when cooled, will snap and return contact 2| tocontact I].

Stop 24 prevents contact I! from following contact 2| when the lattermoves on overload, but permits wear adjustment of the contacts.

Now having described the switch and circuit breaker herein disclosed,reference should be had to the claims which follow:

I claim:

1. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the contact will move automatically on the arising ofa circuit overload out of its normal position, a second contact, aspring and handle actuated operating mechanism for moving the second contact to and from the normal position of the first contact, the operativeconnection between the handle and the second contact being so arrangedthat the handle thereof may be held without restraining automaticmovement of the first contact away from its normal position on thearising of an overload.

2. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the contact will move automatically on the arising ofa circuit overload out of its normal position, a second contact, aspring and handle actuated operating mechanism for moving the'secondcontact to and from the normal position of the first contact, theoperative connection between the handle and the second contact being soarranged that the handle thereof may be held without restrainingautomatic movement of the first contact away from its normal position onthe arising of an overload, the bimetal strip being so constructed as toimpart a snap action movement to the first contact in moving it out ofits normal position.

3. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the contact will move automatically on the arising ofa circuit overload out of its normal position, a second contact, aspring and handle actuated operating mechanism for moving the secondcontact to and from the normal position of the first contact, theoperative connection between the handle and the second contact being soarranged that the handle thereof may be held without restrainingautomatic movement of the first contact away from its normal position onthe arising of an overload, the operating mechanism being so constructedas to give a snap action movement to the second contact in itsmovements.

4. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the contact will move automatically on the arising ofa circuit overloadout of its normal position, a second contact, a springand handle actuated operating mechanism for moving the second contact toand from the normal position of the first contact, the operativeconnection between the handle and the second contact being so arrangedthat the handle thereof may be held without restraining automaticmovement of the first contact away from its normal positon on thearising of an overload, the bimetal strip being so constructed as toimpart a snap action movement to the first contact in moving it out ofits normal position, the operating mechanism being so constructed as togive a snap action movement to the second contact in its movements.

5. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the contact will move automatically on the arising ofa circuit overload out of its normal position, a second contact, aspring and handle actuated operating mechanism for moving the secondcontact to and from the normal position of the first contact, theoperative connection between the handle and the second contact being soarranged that the handle thereof may be held without restrainingautomatic movement of the first contact away from its normal position onthe arising of an overload, the spring of said mechanism constantlytendingto bias the second contact towards and against the first contactwhen the handle of said mechanism is in the closed circuit position,said mechanism being arranged to permit said second contact to move alimited extent while in engagement with the first contact, towards andbeyond the normal closed circuit position of the first contact tocompensate for wear of the parts, and. a stop for arresting movement ofthe second contact, while the handle of the mechanism is in circuitclosing position, beyond a predetermined point, whereby the secondcontact will not follow the first contact when the latter is moved awayfrom the second contact on overload.

6. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the contact will move automatically on the arising ofa circuit overload out of its normal position, a second contact, aspring and handle actuated operating mechanism for moving the secondcontact to and from the normal position of the first contact, theoperative connection between the handle and the second contact being soarranged that the handle thereof may be held without restrainingautomatic movement of the first contact away from its normal position onthe arising of an overload, the bimetal strip perating thereafter forautomatically returning the first contact to its normal position, inengagement with the second contact, provided the handle of saidmechanism has not been moved out of closed circuit position.

7. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the contact will move automatically on the arising ofa circuit overload out of its normal position, a second contact, aspring and handle actuated operating mechanism for moving the secondcontact to and from the normal position of the first contact, theoperative connection between the handle and the second contact being soarranged that the handle thereof may be held without restrainingautomatic movement of the first contact away from its normal position onthe arising of an overload, the bimetal strip operating thereafter forautomatically returning the first contact to its normal position, inengagement with the seccond contact, provided the handle of saidmechanism has not been moved out of closed circuit position, with a timedelay occasioned by the time which is required for the bimetal strip tocool before it can return the first contact to its normal position.

8. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the contact will move automatically on the arising ofa circuit overload out of its normal position, a second contact, aspring and handle actuated operating mechanism for moving the secondcontact to and from the normal position of the first contact, theoperative connection between the handle and the second contact being soarranged that the handle thereof may be held without restrainingautomatic movement of the first contact away from its normal position onthe arising of an overload, the bimetal strip operating thereafter forautomatically returning the first contact to its normal position, inengagement with the second contact, provided the handle of saidmechanism has not been moved out of closed circuit position, the springof said mechanism constantly tending to bias the second contact towardsand against the first contact when the handle of said mechanism is inthe closed circuit position, said mechanism being arranged to permitsaid second contact to move a limited extent while in engagement withthe first contact, towards and beyond the normal closed circuit positionof the first contact to compensate for wear of the parts, and a stop forarresting movement of the second contact, while the handle of themechanism is in circuit closing position, beyond a predetermined point,whereby the second contact will not follow the first contact when thelatter is moved away from the second contact on overload.

9. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the contact will move automatically on the arising ofa circuit overload out of its normal position, a second contact, aspring and handle actuated operating mechanism for moving the secondcontact to and from the normal position of the first contact, theoperative connection between the handle and the second contact being soarranged that the handle thereof may be held without restrainingautomatic movement of the first contact away from its normal position onthe arising of an overload, the bimetal strip operating thereafter forautomatically returning the first contact to its normal position, inengagement with the second contact, provided the handle of saidmechanism has not been moved out of closed circuit position, with a timedelay occasioned by the time which is required for the bimetal strip tocool before it can return the first contact to its normal position, thespring of said mechanism constantly tending to :bias the second contacttowards and against the first contact when the handle of said mechanismis in the closed circuit position, said mechanism being arranged topermit said second contact to move a limited extent while in engagementwith the first contact, towards and beyond the normal closed circuitposition of the first contact to compensate for wear of the parts, and astop for arresting movement of the second contact, while the handle ofthe mechanismis in circuit closing position, beyond a predeterminedpoint, whereby the second contact will not follow the first contact whenthe latter is moved away from the second contact on overload.

10. In a switch, a contact, a bimetal strip ,di-

rectly determining its position, whereby the contact will moveautomatically on the arising of a,

circuit overload out of its normal position, a second contact, a springand handle actuated operating mechanism for moving the second contact toand from the normal position of the first contact, the operativeconnection between the handle and the second contact being so arrangedthat the handle thereof may be held without restraining automaticmovement of the first contact away from its normal position on thearising of an overload, theoperating mechanism being so constructed asto give a snap action movement to the second contact in its movements,the spring of said mechanism constantly tending to bias the secondcontact towards and against the first contact when the handle of saidmechanism is in the closed circuit position, said mechanism beingarranged to permit said second contact to move a limited extent while inengagement with the first contact, towards and beyond the normal closedcircuit position of the first contact to compensate for wear of theparts, and a stop for arresting movement of the second contact, whilethe handle of the mechanism is in circuit closing position, beyond apredetermined point, whereby the second contact will not follow thefirst contact when the latter is moved away from the second contact onoverload.

- 11. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the 'contact will move automatically on the arising ofa circuit overload out of its normal position,- a second contact, aspring and handle actuated operating mechanism for moving the secondcontact to and from the normal position of the first contact, theoperative connection between the handle and the second contact being soarranged that the handle thereof may be held without restrainingautomatic movement of the first contact away from its normal position onthe arising of an overload, the bimetal strip being so constructed as toimpart a snap action movement to the first contact in moving it out ofits normal position, the bimetal strip operating thereafter forautomatically returning the first contact to its normal position, inengagement with the second contact, provided the handle of saidmechanism has not been movedtout of closed circuit position.

12. In a switch, a contact, a bimetal strip directly determining itsposition, whereby the contact will move automatically on the arising ofa circuit overload out of its normal position, a second contact, aspring and handle actuated operating mechanism for moving the secondcontact to and from the normal position of the first contact, theoperative connection between the handle and the second contact being soarranged that the handle thereof may be held without restrainingautomatic movement of the first contact away from its normal position onthe arising of an overload, the bimetal strip being so constructed as toimpart a snap action movement to the first contact in moving it out ofits normal position, the bimetal strip operating thereafter forautomatically returningthe first contact to itsnormal position, inengagement with the second contact, provided the handle of saidmechanism has not been moved out of closed circuit position, with a timedelay occasioned by the time whic is required for the bimetal strip tocool before t can return the first contact to its normal position. v

ROBERT L. FRANK.

